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Sodium: The Silent Killer in Hydroponics · Hydroponics Daily

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Hello and welcome back to Hydroponics Daily, your go-to podcast for everything soilless cultivation.
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I'm your host, Dr. Russell Sharp, the owner of Utrema Limited.
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And at Utrema we make a number of fertilisers, biostimulants.
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Biofungicides, things like this, but we don't make anything made with salt or
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sodium-containing compounds.
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And that's because sodium is really toxic to plants and I'm going to talk about
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how you should avoid sodium in your hydroponic setup, which is not as easy as it sounds.
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You know, you're not going to be pouring salt in there unless you're growing halophytes.
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Halophytes are salt-loving, sodium-loving plants from the seaside and from estuaries
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and things like this. Not many crops are halophytes.
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And so you want to avoid sodium. One of the things I used to do as a lecturer
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at college was get a tomato plant and sit it on my desk at the front of the
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lecture theatre and then just
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put one teaspoon of salt on the top of the soil surface and water it in.
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And by the end of the lecture, in 45 minutes, one hour's time,
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the tomato plant would have keeled over and would be dead.
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And that was to illustrate during that lecture that sodium is one of the most
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toxic things you can give to a plant, probably the most toxic thing you can
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give to a plant and it kills it instantly and is instantly,
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toxic to plants so you think about some herbicides some weed killers that take.
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Weeks to work salt works instantaneously
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and not only that salt sticks around so if
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you try and grow any other plant in that soil it will be poisoned by the salt
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whereas a weed killer like glyphosate is deactivated as soon as it hits the
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soil so that's a big you know reason that's a good reason to avoid salt and
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sodium containing compounds but let's go into the reasons why it's so toxic.
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One of the main reasons people cite is osmotic stress and that's because high
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salt concentrations outside the roots reduce the plant's ability to absorb water
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leading to dehydration even when there's lots of water in the soil.
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So this is by the process of osmosis. It increases the osmotic pressure pull
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coming out of the roots and so the plants can't pull it in through osmosis, through the root cells.
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Now, osmotic stress is not the main reason that salt is toxic there,
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even though it's the most commonly cited reason.
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If you think about it, sugars are osmotic agents as well.
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And when we put sugar compounds onto the plants in flowering,
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if you're growing legal cannabis, that's very, very common.
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Sort of booster, hardener type products. That doesn't
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kill the plant and so it can't just be due to osmotic stress
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it will limit water uptake but
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it won't kill the plant you think of products like a
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very very common product would be like rock resonator if
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you've come across that product full of sugars honeycomb
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in emerald harvest that's
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another popular one there are loads of sugar-based products
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though on the market and they don't kill the plants that
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don't contain sodium the main reason is iron toxicity excess sodium na plus
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and chloride cl minus ions disrupt normal cellular process damaging membranes
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and enzymes and that's the main reason it's like i always like to say sodium is the arsenic.
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To plants so you wouldn't eat a sandwich containing arsenic
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and the plant wouldn't eat a sandwich containing sodium it
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can also lead to certain nutrient imbalances because sodium competes with
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essential nutrients especially potassium and
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sometimes calcium and magnesium leading to deficiencies so
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if you have near the seaside if
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there's a tsunami or an inundation a storm surge
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then plants and crops that have been inundated with salt
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water seawater often show signs of potassium deficiency
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and then sodium will also lead to
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chlorosis which is the yellowing of leaves and necrosis which
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is the dying off of tissues especially it damages
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chloroplasts causing the yellowing and tissue death
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and it just limits growth as well energy is
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diverted to iron regulation and osmotic protection to
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basically the plant diverts attention to overcoming those
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problems and it reduces growth flowering and
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yield so that's the main one and then secondary effects
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salt damages the soil and can
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lead to compaction and degradation to
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soil structure so that can be overcome by applying calcium products and that's
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where utrema sell a lot of products into soil based systems for that but where
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is the sodium coming from in hydroponics because you're not going to be thinking
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you're going to be adding it well you basically it's coming from inferior ingredients.
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If you're growing from a source that uses low-grade potassium nitrate,
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then it contains sodium impurities.
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Again, calcium nitrate can carry sodium contaminants, especially the cheap lower purity ones.
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And then also, one that's not often understood by many formulators of fertilizers
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is that a lot of the micronutrients,
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a lot of the EDTA type fertilizers, if you don't choose the right one then they
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contain lots of sodium so at utreema we always use sodium free,
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micronutrient cellates but lots and lots of companies don't
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and so that will be a big source of sodium and
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then sodium nitrate sometimes used as
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a nitrogen source in some systems but i would always avoid
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it irrigation water groundwater municipal water
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can contain dissolved sodium as well so always always useful
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to clean up your water if you've if you've got the time and
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money ph adjusters never use
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sodium bicarbonate or sodium hydroxide for alkalinity
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control they won't be in most ph
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adjusters though most of them are potassium hydroxide however you will see bicarbonate
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of soda advertised and recommended for controlling a lot of fungal diseases
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never use sodium bicarbonate or bicarbonate of soda because the sodium will be toxic to your plants,
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the bicarbonate is toxic to the fungus.
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Always use potassium bicarbonate.
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The potassium will provide a nutrient, the bicarb will control the fungus.
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If you're growing in cocoa, in coconut fibre, then there is a real possibility
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that you could be getting sodium toxicity from your grow media.
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Coconuts grow near the sea on saline soils and they can contain a lot of sodium.
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And to overcome this, good grow media is buffered and soaked in calcium nitrate to remove the sodium.
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Calcium is really good at removing sodium it leaches it
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out however poor quality cheap growing
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media where they've cut corners you could still get residual sodium and
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then this can appear on your plants when
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you're doing it the other sources recycled nutrient.
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Solutions reusing solutions without adequate
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monitoring them if you reuse growing media
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again you could you could do this and then also
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organic fertilizers anything
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that's used from anything that's created from waste
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food material sort of digestates and
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things like this yes they might be organic yes they
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might be not vegetarian but they could contain
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salt because we put salt
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in food and then when it goes to the digestate to the
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composter the composting process the
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digestive the anaerobic digestion process either one that's
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being used doesn't remove the salt and so that can they
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can be a source of of salt and even
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seaweed extracts contain some small amounts of sodium
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however it's normally quite low the sodium content
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of seaweed extracts some people might say sodium
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is a plant nutrient and plants need
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it but there's always enough contaminants of sodium around
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you don't need to worry ever about adding sodium so
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the best formulators don't use
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sodium and use very high grade purity ingredients
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and then the cheap and cheerful ones you might get some sodium levels
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in there so just be aware of that but for
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the same reason never ever try and
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kill slugs and snails by putting salt on
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them because they will poison your garden by by
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doing that and never put them on your driveway because.
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Again yeah well you could put them on your driveway is
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more it could wash into your garden there could be
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an issue there so always better to use
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a approved method to kill
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slugs and snails and um and for
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weeds never use them to control weeds in your garden some people
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have we often get reports like people phoning up
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and saying that they've killed slugs or they've killed
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weeds with salt and now their garden doesn't grow
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what can I do so for that we recommend applying our liquid chips and product
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which soaks in and dissipates the sodium but it's not really one for hydroponics
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and hydroponics it's best to avoid it in the first place in arid regions or
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regions where there's low water availability then.
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Desalination plants will be providing the water and often you can grow plants
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in water with higher salt levels than would be tolerated with drinking water
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and so there will always be a residual.
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Problem with salinity in those sorts of areas and so
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something you have to deal with and might be you
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have to choose your crops accordingly so desalination plants
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and are used to grow crops in many regions of the world like
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morocco and the middle east and even places
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that you would think we've got loads of water i think
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we might even have a desalination plant in the uk down in cornwall even
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though it rains all the time here so yes desalination
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will remove some sodium but it won't remove
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all the sodium and so you'll have issues there and certainly
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in north africa there's issues and
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and india particularly the use of sodium
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rich water for irrigation of
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fields has made many areas unsuitable
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for growing crops and now in.
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India there are places where you can't grow cereal crops but
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you can grow ornamental plants because they are more tolerant
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to the sodium levels but something you have to understand is that
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once the water's evaporated the sodium remains and
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so if you're constantly irrigating in areas
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with high levels of evaporation then you'll just
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get sodium buildup and you could ruin your farmland by
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doing that and then in these regions that's one of
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the reasons why they've moved to hydroponics as well because you
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can't use the land because it's been too enriched with sodium so something to
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consider places like israel where they grow samphire they're obviously that's
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that's extremely tolerant of salt so that will grow in the regions where they've
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messed up the soil to put it lightly okay so that's been.
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Hydroponics daily for today the reasons why sodium is poisonous and where you
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might get issues with it why not have a look on the side of some of the additive
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ingredients you use in your hydroponic grow and see if sodium is an ingredient
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in them you might be surprised some of them might contain high levels of sodium
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and if so you might want to look for an alternative,
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if you have used a sodium-based product and you thought it was fantastic then
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let me know one i just thought of one one very common.
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Source of sodium is in insecticidal soaps
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they contain the cheap ones well
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not even the cheap ones a lot of them contain sodium-based surfactants
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and this is just stupid at utrema
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we use potassium and magnesium and a
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variety of other cation-based surfactants
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to avoid sodium so we always keep.
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Sodium out of even our soap our soap based products but
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the cheap ones will will contain so sodium dodecal
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sulfate or sodium lauryl sulfate and
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sodium lauryl ether sulfate there's loads of them but they
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all the lot of them contain sodium and then i was going to say you know the cheap
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and cheerful ones but there are a lot of expensive hydroponic plant
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washes and insecticidal soaps that
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contain sodium and that'll be a problem
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because you're applying them as a foliar spray and so
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when you when you see a lot of people saying oh you know
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this is a lights switch with the spray this
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with the lights off because you know the lights might harm it
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when it is it could be that it's just because the sodium content
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in that in that wash is is causing
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the issue so yeah a lot i don't know why so many
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formulators do it because it's not it's not like formulating
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with an alternative is that much more expensive but maybe
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they they've got shareholders and saving the they
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have to shave the pennies and increase the profit margin wherever
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they can at you tremer as i'm the founder and
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owner i can do what's best for the plants and best
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for your crop and best for you rather than actually what's best for the bank
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balance and produce a better product for the same price so check your check
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your ingredients especially your insecticidal soap any pest and disease control
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products see if they contain sodium and if you want help looking for an alternative
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let me know that's been hydroponics daily for today thank you very much for
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listening it's the weekend,
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and I shall see you tomorrow. Goodbye.